414 Transactions. — Zoology. 



the ventral side, its walls are seen to be perforated with a number of aper- 

 tures, by one of which {s.v'), situated at its anterior end, it pours its blood 

 into its sinus venosus, while by the remaining six it receives either blood 

 or lymph from the various parts of the body. One, on the inner wall and 

 somewhat dorsal in position, leads into the jugular vein, by which the 

 blood is brought back from the head {ju') : a small aperture just anterior 

 to this leads into the inferior jugular vein {i.ju') : a large one just pos- 

 terior to that of the jugular is connected with the cardinal veins, by which 

 the blood is returned from the hinder parts of the body {cd') ; on the ventral 

 wall is the entrance of the hepatic sinus (h.s') ; and on the outer wall that 

 of the brachial vein {br'). Lastly, on the dorsal wall is a transverse slit, 

 guarded by a pair of valves, and leading into a large lymph sinus {ly'). 



The jugular (ju.) is a large vein lying to the dorsal side of the gills, and 

 receives the greater part of the blood from the head, the small inferior 

 jugular fi.ju) receiving mainly that from the floor of the mouth and the 

 pericardiiim. The brachial /ir J is a large vein, and receives all the blood 

 from the great pectoral fins ; at its distal end it is connected with the veins 

 belonging to the posterior part of the body, in a way presently to be des- 

 cribed. 



The portal vein returning the blood from the abdominal viscera (fig. 2) 

 is made up of two chief factors, the gastric (fig. 2g.) from the stomach and the 

 mesenteric (ms.) from the intestines. The latter is made up of a main trunk 

 ('»?s'j from the colon — i.e., that part of the intestine in which the spiral 

 valve is contained, a duodenal vein (du.) from the bursa entiana or duodenum, 

 a splenic vein (spl.) from the spleen, and about three small veins (pn.) from 

 the pancreas. The main portal vein fp.J enters the liver, and the blood 

 taken by it to that organ, along with that from the hepatic artery, is poured 

 by several veinlets into the hepatic sinus (fig. 1, h.s.), a large transverse 

 chamber, just anterior to the liver, and opening at either end into the 

 precaval sinuses. 



So far, everything, with the exception of the inferior jugular vein, is 

 just as I have learned it from Prof. Huxley's lectures, and as it is, if my 

 recollection serves me, described by Monro. 



The unpaired caudal vein (c), bringing the blood from the tail, divides 

 immediately on leaving the haemal canal of the caudal vertebrae into two 

 vessels, the renal portal veins (r.p.J which pass, one to each kidney, running 

 up to the greater length of its inner border. Into each renal portal vein 

 open a number of lesser trunks (r.p.' ) from the pelvic and lumbar regions 

 as well as from the region of the vertebral column as far forward as the 

 anterior end of the kidneys ; while from it numerous offshoots (r.p,") pass 

 into and break up in the substance of the kidneys ; so that all the blood 



